Ecdysterone and juvenile hormone (JH) are the primary endocrine regulators of reproduction and development in insects. The mechanism of action of JH is much more poorly understood than that of ecdysterone, due primarily to our dismal knowledge of the JH receptor and JH-regulated genes. The Methoprene-tolerant (Met) bHLH-PAS gene of Drosophila melanogaster is involved in the action of JH, and it can serve as a key to understanding the molecular action of this hormone in both D. melanogaster and mosquitoes. The proposed work is a genetic approach that will accomplish four objectives: First, the Met+ homologous gene from the aedine mosquito Aedes aegypti will be isolated and sequenced. Ae. aegypti is a well-studied disease vector, and this effort will begin an understanding of the JH receptor in mosquitoes. Second, an enhancer/suppressor screen of mutants that interact with Met will be carried out to define the JH receptor complex and related proteins. Third, both point and deletion mutagenesis of Met will be carried out to define the region(s) of MET critical for the functions of this gene. Finally, genes that are transcriptionally controlled by JH (JH target genes) will be identified by DNA micro-array analysis. Identification of these genes will help us understand JH roles and in future work will permit construction of a reporter gene assay for JH to facilitate further molecular analysis of JH signal transduction. [unreadable] [unreadable] This work will have significance for understanding the JH receptor in a genetically well-defined insect. It will lead to a better understanding of the action and insect resistance to the insecticide methoprene, which is used to control mosquito vectors of disease. In addition, a better understanding of Met as a bHLH-PAS gene will further our knowledge of this family of transcriptional regulators, including homologous genes found in humans. [unreadable] [unreadable]